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Decide on Strategy for Preview Environments (e.g. Review Apps)

Considerations​

  • Use as few AWS proprietary services (E.g DynamoDB, SNS, SQS) because provisioning terraform for ephemeral environments is very slow, complicated and therefore not recommended

  • Use instead as many tools that have managed service equivalents in AWS (DocumentDBMongoDB container, MSKKafka container, MySQL, Postgres)

  • Usage of API Gateway will require running terraform and will complicate preview environments

  • Preview environments are poor substitutions for remote development environments due to the slow feedback loop (e.g. commit, push, build, deploy)

  • Preview environments are not a replacement for staging and QA environments, which should have configurations that more likely resemble production

  • Multiple microservices are much harder to bring up if any sort of version pinning is required

Use helmfile with raw chart​

caution

We do not recommend this approach.

Pros​

  • Very rapid to prototype; no need to commit to any chart or convention

  • Repos/apps share nothing, so they won’t be affected by breaking changes in a shared chart (mitigated by versioning charts)

Cons​

  • This is the least DRY approach and the manifest for services are not reusable across microservices

  • Lots of manifests everywhere leads to inconsistency between services; adding some new convention/annotation requires updating every repo

  • No standardization of how apps are described for kubernetes (e.g. what we get with a custom helm chart)

Use helmfile with custom chart​

Slight improvement over using helmfile with the raw chart.

Pros​

  • Re-useable chart between services; very DRY

  • Chart can be tested and standardized to reduce the variations of applications deployed (e.g. NodeJS chart, Rails chart)

  • More conventional approach used by community at large (not cloudposse, but everyone using helm and helmfile)

Cons​

  • Using helmfile is one more tool; for new comers they often don’t appreciate the value it brings

  • CIOps is slowly falling out of favor for GitOps

Use GitHub Actions directly with helm​

Pros​

  • Very easy to understand what is happening with “CIOps”

  • Very easy to implement

Cons​

  • No record of the deployed state for preview environments in source control

  • Requires granted direct Kubernetes administrative access GitHub Action runners in order to deploy helm charts

  • GitHub Action runners will need direct access to read any secrets needed to deploy the helm releases. (mitigation is to use something like sops-operator or external-secrets operator)

Use GitHub actions with ArgoCD and helm​

For some additional context on ArgoCD Decide on ArgoCD Architecture

Requirements​

  • How quickly should environments come online? e.g. 5 minutes or less

  • How many backing services are required to validate your one service?

  • Do you need to pin dependent services at specific versions for previews? - if so, rearchitect how we do this

  • How should we name DNS for previews?

  • The biggest limitation is ACM and wildcard certs, so we’ll need a flat namespace

  • https://pr-123-new-service.dev.acme.org. (using the *.dev.acme.org ACM certificate)

  • URLs will be posted to GitHub Status API to that environments are directly reachable from PRs


  • Do we need to secure these environments? We recommend just locking down the ALB to internal traffic and using VPN

  • How will we handle databases for previews? How will we seed data. Decide on Database Seeding Strategy for Ephemeral Preview Environments

  • What is the effort to implement ArgoCD?

  • Very little, we have all the terraform code to deploy ArgoCD

  • We need to change the GitHub Actions to:

  • build the docker image (like to do)

  • render the helm chart to the raw k8s manifests

  • commit the manifests to deployment repo when ready to deploy

  • What is the simplest path we could take to implement and that developers will have the easiest time understanding?

Patterns of Microservices​

This is more of a side note that not all microservices organizations are the same. If you’re using microservices, please self-identify with some of these patterns as it will be helpful in understanding the drivers behind them and how they are implemented.

  1. As a result of acquisitions

  2. As a result of architecture design from the beginning (this premature)

  3. As a result of needing to use different languages for specific purposes

  4. As a result of seeing performance needs to scale

  5. If this is the case, we technically don’t need to do microservices; we just need to be able to control the entry point & routing (e.g. a “Microservices Monolith”)

  6. For this to work, the monolith needs to be able to communicate with itself as a service (e.g. gRPC) for local development. We see this with Go microservices; this can be done when it’s necessary as a pattern to scale endpoints

  7. Preview environments can still use the gRPC but over localhost

  8. As a result of wanting to experiment with multiple versions of the same service (E.g. using a service mesh)

Decide on Strategy for Preview Environments (e.g. Review Apps)

caution

Internal preview environments cannot accept webhook callbacks from external services like twilio